/**
 * (C) Copyright IBM Corp. 2010, 2015
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * 
 */

package com.ibm.bi.dml.runtime.controlprogram.parfor.opt;

import com.ibm.bi.dml.runtime.DMLRuntimeException;
import com.ibm.bi.dml.runtime.controlprogram.ParForProgramBlock.POptMode;
import com.ibm.bi.dml.runtime.controlprogram.parfor.opt.PerfTestTool.TestMeasure;


/**
 * Heuristic ParFor Optimizer (time: O(n)):
 * 
 *  
 */
public class OptimizerHeuristic extends OptimizerRuleBased
{

	
	public static final double EXEC_TIME_THRESHOLD = 60000; //in ms
			
	@Override
	public CostModelType getCostModelType() 
	{
		return CostModelType.RUNTIME_METRICS;
	}

	@Override
	public PlanInputType getPlanInputType() 
	{
		return PlanInputType.RUNTIME_PLAN;
	}
	
	@Override
	public POptMode getOptMode() 
	{
		return POptMode.HEURISTIC;
	}

	////////////////////////////////////////////////////
	// Overwritten rewrites (see rulebased optimizer) //
	////////////////////////////////////////////////////
	
	/**
	 * Used as one condition in rewriteSetExecutionStategy in order to decide if
	 * MR execution makes sense if all the other constraints are given. 
	 */
	@Override
	protected boolean isLargeProblem(OptNode pn, double M)
	{
		boolean ret = false;
		
		try 
		{
			double T = _cost.getEstimate(TestMeasure.EXEC_TIME, pn);
			ret = (T >= EXEC_TIME_THRESHOLD) && (M > PROB_SIZE_THRESHOLD_MB );
		} 
		catch (DMLRuntimeException e) 
		{
			LOG.error("Failed to estimate execution time.", e);
		}
		
		return ret;
	}

}
